NMSU's Apache Point Observatory Team Observes Record 103,000 Spectra in March

New Mexico State University News Release

2012 April 23

LAS CRUCES, NM - When the sun goes down, researchers and staff at New Mexico State University's Apache Point Observatory go into high gear, mapping the universe one pinpoint at a time for the Sloan Digital Sky Survey III project. The work can be tedious, but the operations team reached a milestone recently by observing a record 103,000 spectra in March for the Baryon Oscillation Spectroscopic Survey.

Typically, BOSS observes 50-60 plates per month. So, who or what can be thanked for this major accomplishment that allowed the Apache Point team to observe 103 plates over a 16-day period? Well, cooperative weather had a little something to do with it.

"We don't have any control over the weather, but we do take credit when it's good," said Mark Klaene, site operations manager. "In order to take advantage of the weather when it is good, a lot of people put in a lot of effort, and that certainly was the case in March. When it happened, everything fell right into place."

When looking up at the sky at night, the light from the objects we detect is really nothing more than a pinhole due to the great distance between the objects and us. To put this work into perspective, Klaene said to image the beam of a flashlight. The tighter the beam of light, the more our eyes are going to see and the more information we can gather. If we are viewing a flood beam, or the light is bouncing around, that light is more dispersed and we are not able to collect as much information.

Cooperative weather for observers is like having that strong, concentrated beam from a flashlight.

This is the most number of spectra that any astronomical survey has ever observed in a month. In fact, no telescopes other than the Sloan 2.5-meter telescope and the Anglo-Australian Telescope have ever even published more spectra than this one-month haul from SDSS-III.

BOSS observes 1000 spectra at a time, organized by "plug plates" whose holes precisely align fiber optic cables that route light from the telescope focal plane to the spectrographs. Each plate has 1000 fibers that are individually plugged by team members. March also saw the first ever "perfect night." Nine plates were observed from start to finish in a single night.

Besides plugging and unplugging plates by hand, researchers also spend their time during the night making constant configuration changes to the telescope and changing plug plates to accommodate time and weather changes. Facing weather and other constraints, the team has a very small observation window. Each takes roughly an hour to collect a complete set of data.

"Extensive planning is done in advance of each observation in order to take maximum advantage of the sky conditions and the available time we can observe from our Earth bound location," Klaene said.

The Sloan Digital Sky Survey, now in its third phase, aims to create a three-dimensional map of our universe. The goal of BOSS is to precisely map out the distances - ranging from redshift galaxies to distant quasars - to study the large-scale structure of the universe, which reflects an imprint of the very early conditions of the universe after the Big Bang. With this information, researchers can study the structure of the universe and how it got to where it is now from a cosmology standpoint.

Klaene said the other nights in March went to other projects that are part of SDSS III or were lost due to bad weather.

"The folks here spend eight hours, 365 days a year, plugging, unplugging, mapping and marking these plates in order for that one fiber, not much larger than a human hair, to collect photons from a distant object and put it into exactly the right place on the spectrograph,' Klaene said. To do that day after day after day - it was a really tremendous effort by the Apache Point team who are a very dedicated crew. It was just amazing to see it happen."